Apartment dwellers, homeowners and others have long been plagued by the inconveniences and lack of security afforded by conventional sliding glass doors. The sliding doors, commonly referred to as "patio doors" are generally light weight structures which have aluminum frame channels in which they slide. Conventional cylinder locks are employed and oftentimes a night latch, dead bolt or door chains are employed from inside to provide additional locking ability. However, the locking mechanisms used to date have not been entirely satisfactory under particular circumstances and the present invention was developed in order to provide a more burglar-proof structure than is presently available.
Another objective of the present invention is to provide a cylinder lock assembly which allows the user to lock or unlock the door from the outside and permits a choice of key withdrawal or locking positions.
It is still another objective of the present invention to provide a locking apparatus having an inside handle which cannot be used to unlock the door with the key withdrawn in a first locking position and whereby the handle can be used to unlock the door if the key is withdrawn from the lock in a second locking position.
It is still another objective of the present invention to provide a door assembly which includes a vertical motion stop means to prevent the door from being pried upwardly and out of its lower channel by burglars or the like.
It is still yet another objective of the present invention to provide a method of securing a door which includes rotating the cylinder means of the locking apparatus in such a direction or directions whereby the user can elect whether to permit the door to be unlocked from the inside by use of the handle.
Other objectives and advantages of the present invention will become clear as the present invention is explained further hereinafter.